scholarly journals Multiple-Locus Sequence Typing Analysis of Bacillus cereus and Bacillus thuringiensis Reveals Separate Clustering and a Distinct Population Structure of Psychrotrophic Strains

2006 ◽  
Vol 72 (2) ◽  
pp. 1569-1578 ◽  
Author(s):  
Alexei Sorokin ◽  
Benjamin Candelon ◽  
Kévin Guilloux ◽  
Nathalie Galleron ◽  
Natalia Wackerow-Kouzova ◽  
...  

ABSTRACT We used multilocus sequence typing (MLST) to characterize phylogenetic relationships for a collection of Bacillus cereus group strains isolated from forest soil in the Paris area during a mild winter. This collection contains multiple strains isolated from the same soil sample and strains isolated from samples from different sites. We characterized 115 strains of this collection and 19 other strains based on the sequences of the clpC, dinB, gdpD, panC, purF, and yhfL loci. The number of alleles ranged from 36 to 53, and a total of 93 allelic profiles or sequence types were distinguished. We identified three major strain clusters—C, T, and W—based on the comparison of individual gene sequences or concatenated sequences. Some less representative clusters and subclusters were also distinguished. Analysis of the MLST data using the concept of clonal complexes led to the identification of two, five, and three such groups in clusters C, T, and W, respectively. Some of the forest isolates were closely related to independently isolated psychrotrophic strains. Systematic testing of the strains of this collection showed that almost all the strains that were able to grow at a low temperature (6°C) belonged to cluster W. Most of these strains, including three independently isolated strains, belong to two clonal complexes and are therefore very closely related genetically. These clonal complexes represent strains corresponding to the previously identified species Bacillus weihenstephanensis. Most of the other strains of our collection, including some from the W cluster, are not psychrotrophic. B. weihenstephanensis (cluster W) strains appear to comprise an effectively sexual population, whereas Bacillus thuringiensis (cluster T) and B. cereus (cluster C) have clonal population structures.

2004 ◽  
Vol 186 (23) ◽  
pp. 7959-7970 ◽  
Author(s):  
Fergus G. Priest ◽  
Margaret Barker ◽  
Les W. J. Baillie ◽  
Edward C. Holmes ◽  
Martin C. J. Maiden

ABSTRACT Representative strains of the Bacillus cereus group of bacteria, including Bacillus anthracis (11 isolates), B. cereus (38 isolates), Bacillus mycoides (1 isolate), Bacillus thuringiensis (53 isolates from 17 serovars), and Bacillus weihenstephanensis (2 isolates) were assigned to 59 sequence types (STs) derived from the nucleotide sequences of seven alleles, glpF, gmk, ilvD, pta, pur, pycA, and tpi. Comparisons of the maximum likelihood (ML) tree of the concatenated sequences with individual gene trees showed more congruence than expected by chance, indicating a generally clonal structure to the population. The STs followed two major lines of descent. Clade 1 comprised B. anthracis strains, numerous B. cereus strains, and rare B. thuringiensis strains, while clade 2 included the majority of the B. thuringiensis strains together with some B. cereus strains. Other species were allocated to a third, heterogeneous clade. The ML trees and split decomposition analysis were used to assign STs to eight lineages within clades 1 and 2. These lineages were defined by bootstrap analysis and by a preponderance of fixed differences over shared polymorphisms among the STs. Lineages were named with reference to existing designations: Anthracis, Cereus I, Cereus II, Cereus III, Kurstaki, Sotto, Thuringiensis, and Tolworthi. Strains from some B. thuringiensis serovars were wholly or largely assigned to a single ST, for example, serovar aizawai isolates were assigned to ST-15, serovar kenyae isolates were assigned to ST-13, and serovar tolworthi isolates were assigned to ST-23, while other serovars, such as serovar canadensis, were genetically heterogeneous. We suggest a revision of the nomenclature in which the lineage and clone are recognized through name and ST designations in accordance with the clonal structure of the population.


2010 ◽  
Vol 105 (2) ◽  
pp. 171-175 ◽  
Author(s):  
Clelton A. Santos ◽  
Gislayne T. Vilas-Bôas ◽  
Didier Lereclus ◽  
Marise T. Suzuki ◽  
Elisangela A. Angelo ◽  
...  

2005 ◽  
Vol 71 (12) ◽  
pp. 8107-8114 ◽  
Author(s):  
Viviane Zahner ◽  
Diana Aparecida Cabral ◽  
Adriana Hamond Régua-Mangia ◽  
Leon Rabinovitch ◽  
Gaétan Moreau ◽  
...  

ABSTRACT One hundred twenty-one strains of the Bacillus cereus complex, of which 80 were isolated from a variety of sources in Brazil, were screened by PCR for the presence of sequences (bceT, hblA, nheBC, plc, sph, and vip3A) encoding putative virulence factors and for polymorphisms in variable-number tandem repeats (VNTR), using a variable region of the vrrA open reading frame as the target. Amplicons were generated from isolates of B. cereus and Bacillus thuringiensis for each of the sequences encoding factors suggested to play a role in infections of mammals. Intriguingly, the majority of these sequences were detected more frequently in Bacillus thuringiensis than in B. cereus. The vip3A sequence, which encodes an insecticidal toxin, was detected exclusively in B. thuringiensis. VNTR analysis demonstrated the presence of five different fragment length categories in both species, with two of these being widely distributed throughout both taxa. In common with data generated from previous studies examining European, Asian, or North American populations, our investigation of Brazilian isolates supports the notion that B. cereus and B. thuringiensis should be considered to represent a single species.


2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Bouziane Moumen ◽  
Christophe Nguen-The ◽  
Alexei Sorokin

Diarrheic food poisoning by bacteria of the Bacillus cereus group is mostly due to several toxins encoded in the genomes. One of them, cytotoxin K, was recently identified as responsible for severe necrotic syndromes. Cytotoxin K is similar to a class of proteins encoded by genes usually annotated as haemolysin II (hlyII) in the majority of genomes of the B. cereus group. The partially sequenced genome of Bacillus thuringiensis var israelensis ATCC35646 contains several potentially induced prophages, one of them integrated into the hlyII gene. We determined the complete sequence and established the genomic organization of this prophage-designated phIS3501. During induction of excision of this prophage with mitomycin C, intact hlyII gene is formed, thus providing to cells a genetic ability to synthesize the active toxin. Therefore, this prophage, upon its excision, can be implicated in the regulation of synthesis of the active toxin and thus in the virulence of bacterial host. A generality of selection for such systems in bacterial pathogens is indicated by the similarity of this genetic arrangement to that of Staphylococcus aureus  β-haemolysin.


2006 ◽  
Vol 188 (21) ◽  
pp. 7711-7711 ◽  
Author(s):  
Cliff S. Han ◽  
Gary Xie ◽  
Jean F. Challacombe ◽  
Michael R. Altherr ◽  
Smriti S. Bhotika ◽  
...  

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